Question

Why would an IT technician ever have to change out a computer’s motherboard?

Answer 1

Here are a couple reasons:
Integrated Ports Gone Bad.
Motherboard is fried from electrical charge.
New features of updates.
Hope this helps.

Answer 2

Answer:

If the Motherboard was shorted out, you would need to change it out then.

If the Capacitor is shorted or it is leaking out acid, if you can't repair it you would then need to replace it.

If the Motherboard itself is cracked.

Dust and debris can make the Motherboard stop working.

If the CPU has fried the motherboard with a max output.  

Explanation: